Stroke varying mechanism for swash plate engines



March 29, 1949. s. B. ECKERT 2,465,638

STROKE VARYING' MECHANISM FOR SWASH PLATE ENGINES Filed May 24, 1945' 2 Sheets-Sheet 1 I u w 0 3 PD u Q K'i Q [R u L: N 4 G w 3H U ,{I Q} *8 f N 'u a o I E WWI/V701? W/TNfSS: A 2 WW]. Smwl. 2,5 C

March 29, 1949.

Filed May 24, 1945 s. B. ECKERT STROKE VARYING MECHANISM FOR 2 SheetS -Sheet 2 SWASH PLATE ENGINES Patented Mar. 29, 1949 UNITED STATES PATENT OFFICE f 2,4s5,sss- STROKE VARYING MECHANISM FOR SWASH PLATE ENGINES Samuel B. Eckert, Haverford, Par, Application May 24,1945 Serial no. 595,592

3 Claims. (01. 123-58) It is well understood that within reasonable limits increasing the compression ratio of an internal combustion engine greatly improves its power output and fuel efficiency. If, however, such an engine is designed for a compression ratio of (say) '7 to 1 and is then operated under normal conditions with the butterfly valve only partially open, the average compression ratio at which the engine operates is only about one quarter of its full capacity. It has been calculated, as well as determined by experiment, that with such reduction in compression ratio the efiiciency of the engine is reduced approximately one half, involving serious waste of fuel.

The object of my invention is to adjustably vary the stroke of the piston (thereby varying the charge admitted to the cylinder) and at the same time maintain constant the ratio of volumes of the cylinder at the two end strokes of the piston; that is, to maintain, at all loads, a constant compression ratio and hence uniform maximum eificiency and fuel economy.

The invention is embodied in an engine of the so-called crankless opposed piston type, in which adjusting means are provided to (l) vary the position of the piston at the end of its'instroke to thereby vary the charge of combustible gases admitted to the cylinder and (2) at the same time vary the length of the stroke of the piston so that the charge drawn into the cylinder will always be compressed to the same predetermined pressure.

A preferred embodiment of the invention is shown in the drawings, in which-- Fig. 1 is a longitudinal section through the engme.

Fig. 2 is a face view of one of the elements of the engine taken on line 2-2 of Fig. 1.

Fig. 3 is a diagram showing how the desired compression ratio may be maintained at different adjustments controlling piston stroke.

The engine is, as hereinbefore stated, of the opposed piston type and comprises cylinders a, within each of which reciprocates opposed pistons b. No mechanism is shown for actuating the inlet and exhaust valves h since these may be of the conventional type actuable by the conventional type of half time cam shaft and valve lifts. Each piston is, through a connecting rod 0, attached, through a universal joint, with an annular collar d, U-shaped in cross-section, at the corresponding end of the engine. Rotatable, in ball and roller bearings, within the collar d at each end of the engine is an annular disc e, the plane of which is inclined to the main drive shaft 1.

Each disc e is carried by a bell-shaped flywheel g secured to the main drive shaft. Each disc is pivoted at h. to the flywheel g and, diametrically opposite thereto, is pivoted to a nut i on a screwthreaded rod is rotatable at opposite ends in lugs on the flywheel. I

From the foregoing description it will be understood that reciprocation of the pistons effects rotation of the discs e, flywheels g and main driving shaft j. i

' Each threaded rod is connected through bevel gears m, shaft 11. and bevel gears o with a shaft p extending through the hollow main driving shaft f. Shaft 17 is driven from a small controllable motor r, which is controlled from the throttle (not shown).

All the mechanism hereinbefore described is duplicated at both ends of the engine, the only difference being that one screw It has a right hand thread and the other a left hand thread, so that, when the motor 1' is rotated, the two discs e are swung together toward, or away from, the engine cylinders.

To offset the tendency of a rotating disc e to impart a similar rotating motion to the corresponding collar d, the collar is provided with pins t that extend into slots u, extending parallel to the main driving shaft,'formedin a frame 21, forming part of the engine casing.

The connection between connecting rods 0 and the pistons bmay be universal joints. If, as shown, the engine is of the four cylinder type, those two connecting rods which are in the plane of the pins t maybe the normal wrist-pin connections as shown, but the connection between the other two connecting rods and the pistons should be universal joints like those illustrated in Fig. 1 between the connecting rods and the U- shaped collar d.

Proper alignment, Withminimum friction, between each of the collars d and the corresponding disc e is insured by the ball and roller bearings to.

Fig. 1 shows each piston b of one pair of pistons at the end of its instroke, and each piston b of the other diametrically opposite pair of pistons at the end of its outstroke. The drawing may also be taken as illustrating the positions of the same pistons b of the same pair at the beginning and end of that half revolution of the flywheel g and shaft 1 which moves such pistons from their extreme instroke positions to their extreme out stroke positions. Making the latter assumption as to the; showing of Figfl, it will be observed that in the upper position of the piston the distance from a plane perpendicular to the axis of the driving shaft intersecting pivot h and the pivot of its connecting rod, to the wobbling annular collar when the piston is at its lower position is (approximately) six times such distance when the piston is at its upper position. When the wobbling annular collar is adjusted so as to (let us say) reduce its angle of inclination to the driving shaft, the relative distances above stated will remain at the 6:1 ratio. Thereby the ratio of volumes of the cylinder between pistons of each pair at their two end strokes will remain constant. The stroke of the piston will. bevaried Without varying the compression in the cylinder as distinguished from known constructions in which the compression in the cylinders varies with variations in the piston stroke. a In other words, the pivot h is so located that any swinging movement of the disc e effects: a variation in the stroke of the pistons but at the same time varies the compression spaces in such a way as to maintain the same compression ratio regardless of the volume of charge taken into the cylinder. This will be clearly understood by reference to Fig. 3. In this figure the discse are adjusted, as shown in full lines, to allow arelatively long stroke of the pistons to thereby admit a relatively large charge. The distance between the pressure face of each piston and the midway point of the cylinder is shown, at the outstroke, as 6 units of measurement and at the instroke as 1 unit of measurement, giving a compression ratio of 6 to 1. When the disc is adjusted to the dotted line position to thereby admit a smaller charge, the distances between the pressure face of each piston and the midway point of the cylinder are reduced (for example) to 3 units at the outstroke and unit at the instroke, giving the same compression ratio of 6 to 1. This ratio is maintained constant regardless of the predetermined length of stroke of the piston. v e It will be understood that my improved construction is sharply distinguishable, as above stated, from constructions that are adapted to be adjusted to vary the compression ratio through varying the length of stroke; my improvement being intended and adapted to avoid any variation in the compression ratio, that is, to maintain.

constant the relationship between the volume of the cylinder with the piston at the bottom of its stroke and the volume of the cylinder with the piston at the top of its stroke, thereby enabling the engine to at all times operate at maximum efficiency and economy.

What I claim and desire to protect by Letters Patent is:

1. In an internal combustion engine of the type comprising a rotatable shaft, two sets of opposed cylinders disposed about said shaft and: having their axes parallel thereto, Wobbler elements, one for each set of cylinders, rotatable with the shaft and mounted thereon, and pistons reciprocatory in said cylinders and operatively connected with said Wobbler elements; the improvement which comprises fiy-wheels secured to the shaft at opposite ends of the engine and a screw-threaded rod rotatable in each fly-wheel, eachfrotatable member being pivotally connected at one side to the corresponding fiy-wheels, a nut at its opposite side engaging the corresponding threaded rod, and means to rotate in unison the threaded rods at opposite ends of the engine. I

2. In an internal combustion engineof the type comprising a rotatable shaft, two sets of opposed cylinders disposed about said shaft and having their axes parallel thereto, Wobbler elements, one for each set of cylinders, rotatable with the shaft and mounted thereon and pistons reciprocatory in said cylinders and operatively connected with said Wobbler elements; the improvement which comprises fly-wheels secured to the shaft at upposite ends of the engine and a screw-threaded rod rotatable in each fly-wheel, each rotatable member being pivotally connected at one side to the corresponding fiy-wheels, a nut at its opposite side engaging the corresponding threaded rod, and means to rotate in unison the threaded rods at opposite ends of the engine, said last named means I comprising a second shaft extending through the main driving shaft, and driving con-. nections from the second shaft to the threaded rods. 1

3. In an internal combustion engine of the type comprising a rotatable shaft, two sets of opposed cylinders disposed about said shaft and having their axes parallel thereto, Wobbler elements, one for each set of cy1inders, rotatable with the shaft and mounted thereon, and pistons reciprocatory in saidcylinders; the improvementwhich comprises members, one at each end of the engine, non rotatable Withth e shaft and pivotally connected with the corresponding pistons and about which said Wobbler elements are circumferenti'ally slidable, means at each endof the engine rotatable with the shaft, each wobbler element being pivoted, to its corresponding rotatable.

means at a radial distance from the shaft greater than h r i i ta e fro e af of t points of connectionbetween the pistons and the non-rotatable member, the distances, from a plane perpendicular to ,the shafts axis and inter secting the pivot of said Wobbler element to the pivotal connection of the corresponding nonrotatable member with each piston varying, in

the full stroke of the pistons, to give, in each cyl-f inden between opposed pistons, maximum and minimum volumes corresponding to a predetermined compression ratio, and adjusting means to swing each Wobbler element on its pivot to change its angle of obliquity to the shaft and thereby increase or decrease said distances.

stir/1on1. B. some.

REFERENCES CITED The following references are of record inthe' file of this patent:

UNITED STATES PATENTS 2,263,561 Bierman Nov. 25; 1941 

